In the manufacture of many pharmaceutical products, such as pills or lozenges, candies such as "M&Ms" or even small mechanical or electronic components, it is often desirable to imprint a trademark, indicia or other information or intelligence on more than one side of each item. These items share a common characteristic in that they are all pellet-like, being small, often round or rounded, oval, bulbous, cylindrical or polygonal in shape. Examples of pellet-like items include pills, lozenges, capsules, tablets and caplets. For convenience the term "pellet" is used hereafter to refer to pellet-like items, it being understood that the term is intended to encompass all manner of small pellet-like items similar to the examples provided above.
Machines for imprinting or "branding" pellets with indicia have long been in use, as exemplified by U.S. Pat. No. 2,859,689 to Ackley. The '689 patent discloses a pellet marking machine (FIGS. 1 and 2) which feeds pellets "P" from a hopper 22 to a rotating drum 23 which has rows of cavities 33, each of which accepts a pellet. Pellets are oriented and retained in the cavities 33 as the drum 23 rotates counterclockwise. Rotation of the drum is synchronized with an endless conveyor 24 which is positioned beneath drum 23. The conveyor has a plurality of carrier bars 110, each of which is transversely mounted on the conveyor and has a row of cavities 140 corresponding to cavities 33 on drum 23. As drum 23 rotates, cavities 33 align with cavities 140 of carrier bars 110 and the pellets are transferred to the conveyor.
The conveyor moves the pellets along a track which passes beneath a means for printing indicia on each pellet, such as the gravure printer comprising ink reservoir 25, transfer roller 26 and printing roller 27 seen in FIG. 2 of the '689 patent. The indicia are engraved on the surface of transfer roller 26 which rotates within ink reservoir 25, the ink being retained in the engravings. Printing roller 27, rotating in contact with the transfer roller, picks up the ink from the engraving and then contacts pellets "P" in carrier bars 110, printing the indicia on each pellet.
Other printing means are also known, such as ink-jet printers or laser printers, which could easily be used in place of the gravure printer shown.
Drum-and-conveyor type marking machines, as described in the '689 patent, are in widespread use in the pharmaceutical and confectionery industries and provide for reliable, high volume, high quality marking of pellets. A problem arises with such marking machines, however, when it is desired to print indicia on more than one side of a pellet. This problem is especially acute for pellets which depart from a round or cylindrical shape and are, therefore, not easily rotatable within the cavity of a carrier bar to expose another side for imprinting. Clearly, there is a need for a device which can be used in conjunction with such marking machines to rotate or invert pellets on the carrier bars to expose another or the opposite side of each pellet. This will allow further imprinting of indicia on each pellet by a second printing means without removing the pellets from the carrier bars.